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Old 01-14-2006, 02:06 PM
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Yorky Yorky is offline
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Watercolor Handbook - Lightfastness and Permanancy of Watercolors

Lightfastness and Permanency of Watercolors by David Lex Rollins

You probably put a lot of yourself into your watercolor paintings: time, energy, concentration, anger, love, blood sweat, & tears. So you sure don’t want your creations to fade, discolor, or otherwise deteriorate. Here are some things to consider to prevent that from happening::

• your paper
• framing and mounting materials
• properly displaying finished watercolors
• and, of course, the pigments in your paints

I’ll concentrate on pigments in this article, but first I’ll briefly touch on the other aspects.

Paper

In my opinion, this is pretty basic – simply use only 100% acid-free (sometimes referred to as pH-neutral) paper.

Framing and mounting

Make sure your framer uses 100% acid-free materials. Everything - the mats, backing, spacers, foam board, even the adhesives should all be acid-free. Although I actually had one framer tell me that it isn’t necessary to go acid-free for watercolors (I refused to give him my business), most reputable framers will use acid-free materials as a matter of course. But certainly make a point of insisting on it just to be safe.

Another practice is to use UV-filtering glass, although it seems that this isn’t common, probably because of the additional expense. It might be worth considering if your painting will be displayed in direct sunlight (something I don’t recommend).

Displaying

A couple of general guidelines:

• Do not display your painting in direct sunlight
• Do not hang your painting in areas of high humidity

Pigments

Some pigments react (fade or discolor) for a variety of reasons - exposure to light is the main one, but acids (see above) and alkalis will damage many pigments, as will atmospheric impurities. However, the prime consideration is the light-fastness of the pigments used in producing the paint. Will it fade? Insisting on using only those paints whose pigments are rated good or excellent in light-fastness is the most important action you can take. Fortunately, most paint manufacturers now label their tubes with the necessary information. Unfortunately, it often takes a magnifying glass to read this, and some solid knowledge to interpret it. In my opinion, you should shun a manufacturer who does not label their tubes with all the information you need to make an informed purchasing decision. If they refuse to tell me what it is that they sell, I won’t buy.

What you want to look for are the actual pigments used in formulating the paint (expressed as both the common name and the Color Index Number), and the permanency rating of the paint. The commonly accepted light-fast rating system is the one from the American Society of Testing and Materials (ASTM). Paints are rated:

I. Excellent light-fastness
II. Very good light-fastness
III. Colors can fade badly, especially the tints
IV. Colors will fade rapidly
V. Colors will bleach very quickly

My strong recommendation is to use only those paints made from pigments in the top two ASTM light-fast categories (I and II).

Until you are comfortable that you know beyond a doubt what pigments to avoid, I recommend that you rely on some good reference material. Two of the best ones are:

Handprint.com

handprint.com offers information on all aspects of watercolors, including the author’s determination of the permanency ratings of many paints. My experience has been that handprint.com provides a lot of useful information, but there is so much there that it might be hard to sift through stuff you’re not interested in and find just what you’re looking for. I’ve also found several cases where the information was outdated – the manufacturer had changed the formulation of paints, but the website still presented the old information. Also keep in mind that the author is unabashedly opinionated.

2) The Wilcox Guide to the Best Watercolor Paints, by Michael Wilcox
This excellent book provides lots of information to help you select the best paints. Make sure the edition you rely on is recent – my local library has only a 5-year-old edition. I have the 2001-2002 edition, and I’ll get the newest one as soon as I see that it’s available.

I prefer this book to handprint.com. But be aware that Michael Wilcox is as opinionated as the author of handprint.com. And just as with handprint.com, I’ve found some outdated information.

Some random thoughts:

• There are a few cases where a manufacturer’s Student Grade of a particular paint is considered almost as good as the Artists Quality paint, and you can get a fine paint at a lower cost. But these cases are rare, so I recommend that you usually stick with the Artists Quality range.
• Don’t rely on the name that the manufacturers give a particular color – they can call it anything they want, and you could end up wasting your money on an inferior paint. On the other hand, a paint could be marketed as Hooker’s Green, yet be made using pigments that are more permanent that the fugitive one used in genuine Hooker’s Green. Since trade names abound, you should rely on the actual pigments used to make your purchasing decisions.
• Be cautious if the paint has “Hue” in the name. Many of these are artificial colors that use pigments different from what you would expect based on the name. For example, one noted manufacturer used to sell a color called Cadmium Yellow Pale Hue. True Cadmium Yellow is made from PY37, which is absolutely light-fast. This hue was made from PY1 (Arylide Yellow) which not only fades quickly, but it also can discolor and/or darken. On a side note, “hues” are often mixed from multiple pigments, and many artists agree that this could more likely lead to muddy colors as opposed to using “single-pigment” paints.

Pigments to avoid (based on poor light-fastness)

This list gives the Color Index Name (example – PY1), the Common Name (example – Arylide Yellow), and the lightfast rating (either from the ASTM or from Michael Wilcox; ratings range from I, which denotes excellent lightfastness, to V, which denotes that the colors will bleach out very quickly), followed in some cases by notes. The information in this section comes from The Wilcox Guide to the Best Watercolor Paints, 2001-2 edition, by Michael Wilcox.

Yellows:

Be very cautious when purchasing yellow paints. In my opinion, only the reds and violets exceed the yellows in the number of inferior pigments being marketed to the public.

PY1 Arylide Yellow G not ASTM tested, Wilcox rating of V
Quickly faded as a wash, and darkened at full strength.

PY1:1 Arylide Yellow G ASTM rating of III
Faded quickly, especially as a thin wash. Also called Hansa Yellow Medium.

PY4 Arylide Yellow 13G not ASTM tested, Wilcox rating of III

PY12 Diarylide Yellow AAA not ASTM tested, Wilcox rating of IV
Will quickly fade. Pigment is also called Benzidine AAA DI.

PY13 Diarylide Yellow AAMX not ASTM tested, Wilcox rating of IV

PY14 Diarylide Yellow OT not ASTM tested, Wilcox rating of IV
Pigment is also known as Benzidine Yellow AAOT.

PY17 Diarylide Yellow AO not ASTM tested, Wilcox rating of V
Thin wash faded rapidly, mass tone became duller.

PY20 Benzidine Yellow B not ASTM tested, Wilcox rating of IV

NY24 Gamboge not ASTM tested, Wilcox rating of V
Washes bleach out rapidly.

PY55 Diarylide Yellow PT not ASTM tested, Wilcox rating of IV
Faded rapidly, especially as a tint.

PY74LF Arylide Yellow 5Gx ASTM rating of III
There are 2 versions – LF (oddly enough meaning Light Fast) and HS (meaning High Strength). Neither is lightfast.

PY100 Tartrazine Lake not ASTM tested, Wilcox rating of V
According to Wilcox, this is an utterly worthless substance for artistic use.

PY110 Isoindolinone Yellow R not ASTM tested, Wilcox rating of III
Wilcox states that this pigment has appeared on the ASTM list as both III (not approved) and I (approved). His testing showed rapid fading.

A few of the Arylide Yellows (PY3, PY65, PY97, and PY152) and the Diarylide Yellows (PY83-HR70 and PY152) are considered acceptable or better.

Oranges:

PO1 Hansa Orange not ASTM tested, Wilcox rating of V

PO13 Pyrazolone Orange not ASTM tested, Wilcox rating of V

PO34 Diarylide Orange not ASTM tested, Wilcox rating of V
Also called Benzidine Orange

Reds:

It seems that the reds and violets have the greatest number of inferior paints marketed to the unwary artist.

PR2 Napthol Red FRR ASTM rating of V

PR3 Toluidine Red not ASTM tested, Wilcox rating of V

PR4 Chlorinated Para Red not ASTM tested, Wilcox rating of V
Tints bleached rapidly, while mass tones became darker and duller.

NR4 Carmine ASTM rating of V
Fades rapidly as a tint, and becomes brownish in mass tone.

PR5 Napthol 1TR ASTM rating of III
According to Wilcox, this pigment is marketed under many other names. So always look for the Color Index Number before shelling out your money.

PR6 Parachlor Red not ASTM tested, Wilcox rating of III

PR7 Napthol AS-TR ASTM rating of III
As with most fugitive pigments, this one faded as a tint and became duller in mass tone.

PR9 Napthol AS-OL ASTM rating of III
This pigment is also called Napthol Bright Red.

NR9 Natural Rose Madder ASTM rating of IV
Be suspicious of anything with “Madder” in the name; make sure you check the Color Index Number before buying.

PR23 Napthol Red not ASTM tested, Wilcox rating of V
According to Wilcox, this pigment is also called Imperse Red. No matter what name you give it, it’s highly unreliable.

PR48:1 Permanent Red 2B (Barium) not ASTM tested, Wilcox rating of V

PR48:2 Permanent Red 2B (Calcium) ASTM rating of IV
Another name for this pigment is Calcium Red 2B.

PR48:4 Permanent Red 2B (Manganese) not ASTM tested, Wilcox rating of II to III
Another name for this pigment is Manganese Red 2B.

PR49:1 Lithol Red not ASTM tested, Wilcox rating of IV

PR53:1 Red Lake C (Barium) not ASTM tested, Wilcox rating of V
Also called Barium Red Lake C.

PR57 Lithol Rubine (Sodium) not ASTM tested, Wilcox rating of V
Better suited as a food colorant than as ab artist’s paint.

PR57:1 Lithol Rubine (Calcium) not ASTM tested, Wilcox rating of V
Also called Rubine 4G.

PR60 Scarlet Lake (Sodium) not ASTM tested, Wilcox rating of V
It seems that a paint with “Lake” in the name should arouse your suspicions.

PR81 Rhodamine Y not ASTM tested, Wilcox rating of V
Also called PTMA Pink.

PR82 Rhodamine Yellow Shade not ASTM tested, Wilcox rating of V

PR83 Rose Madder, Alizarin ASTM rating of IV
If you get nothing else out of this article, please remember that PR83 should be avoided at all costs.

PR83:1 Alizarin Crimson not ASTM tested, Wilcox rating of IV
I am appalled that even reputable manufacturers still offer Alizarin Crimson, knowing full well that it is very fugitive. Perhaps it’s because many noted artists continue to recommend Alizarin Crimson in their books (which is as just as unethical as the paint companies selling it.)

PR90 Phioxine Red not ASTM tested, Wilcox rating of V
Also called Eosine.

PR105 Red Lead not ASTM tested, Wilcox rating of V
It blackens upon exposure to the Hydrogen Sulphide in the atmosphere.

PR106 Vermilion ASTM rating of III
Fortunately, genuine Vermilion is becoming rare. Wilcox notes that it is quite unreliable and becomes very dark, and he suggest a rating of V.

PR112 Napthol AS-D ASTM rating of III
This pigment is produced under a variety of names, one of which is Permanent Red FGR.

PR122 Quinacridone Magenta ASTM rating of III
Wilcox comments that some companies disagree with this rating, considering it to be more lightfast. So you may see a higher rating in their literature. The obvious lesson is to be wary of marketing claims.

PR146 Napthol Red not ASTM tested, Wilcox rating of IV

PR173 Rhodamine B not ASTM tested, Wilcox rating of V
Wilcox notes that this pigment uses the same dye as the “equally fugitive PV!.”

PR177 Anthraquinoid Red ASTM rating of III
Although Wilcox says this is ASTM III, in another section he says “It has now been tested as ASTM II.” Since I don’t know which is correct, I choose to err on the side of caution, so I’ll avoid this pigment in favor of more reliable alternatives.

PR181 Thioindigoid Magenta not ASTM tested, Wilcox rating of IV

PR210 Permanent Red F6RK not ASTM tested, Wilcox rating of V
I agree with the opinion that Wilcox offers: “I have become very wary of Paints and pigments with the word ‘permanent” in their title, as it usually indicates quite the opposite.

Violets:

You’ll find many of the same inferior pigments here as you saw in the Reds section above.

PV1 Rhodamine B not ASTM tested, Wilcox rating of V
According to Wilcox, the parent dye is called Basic Violet 10.

PV2 Rhodamine 3B Lake ASTM rating of IV

PV3 Methyl Violet not ASTM tested, Wilcox rating of V

PV4 Magenta not ASTM tested, Wilcox rating of V

PV5AL Alizarin Maroon ASTM rating of V
Wilcox says that this pigment is even less resistant to light than PR83, the pigment is Alizarin Crimson.

PV23BS or RS Dioxazine Purple ASTM rating III to IV
The RS (Red Shade) has the III, and the BS (Blue Shade) has the IV. You should avoid both.

PV39 Crystal Violet not ASTM tested, Wilcox rating of V
Wilcox calls this “…a disastrous substance which to my mind has no place whatsoever amongst artists’ watercolors.”

Blues:

Good news!!! Most of the pigments used to produce blue watercolor paints are lightfast. Here are a few exceptions:

PB1 Victoria Blue not ASTM tested, Wilcox rating of V
“…unsuitable for artistic use.”

PB17 Phthalocyanine Blue not ASTM tested, Wilcox rating of III
Note that most Phthalo Blues use better pigments (PB15 and PB16). But this pigment is best avoided. In other words, read the label carefully, because some manufacturers may sneak in PB17, making an reliable sounding paint inferio.

PB24 Fugitive Peacock Blue not ASTM tested, Wilcox rating of V
Wilcox says” “this pigment, without any doubt, takes my vote as the most unsuitable substance for artistic use that I have ever come across.” Nothing else needs to be said.

Greens:

Just as with the blues, most green paints are made with reliable pigments. Here are a few to be wary of:

PG1 Brilliant Green not ASTM tested, Wilcox rating of V
Thinner washes faded, mass tones darkened. Also poor alkali resistance.

PG8 Hooker’s Green ASTM rating of III
I was surprised to find this popular pigment to be less than lightfast.

PG12 Napthol Green ASTM rating of IV
It looks like anytime you see the word “Napthol”, you should proceed carefully.

Browns:

There are only a few brown pigments to watch out for.

NBr8 Van Dyke Brown not ASTM tested, Wilcox rating of IV
Especially fugitive in a thin wash.

PBr8 Manganese Brown not ASTM tested, Wilcox rating of IV
Wilcox says that this is reported to be reliable, but he has not seen test results to verify it. His tests showed this to be an inferior pigment, which faded quickly and discolored.

Useful Threads

I investigated many threads that included the terms “permanent”, “lightfast”, and “ASTM”. Generally, they were all similar, and I didn’t see any information that I have not already included above.

Here are three representative threads:

Aureolin Alert

lightfastness

lightfastness update

Last edited by Yorky : 01-14-2006 at 02:19 PM.

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